The human spine is arranged as a series of vertebrae separated by intervertebral discs often referred to as the backbone. These intervertebral discs perform a variety of functions. In particular the discs allow the spine to twist and flex as well as functioning as a cushion to absorb force or shock between adjacent vertebrae. Spinal discs are subject to physical degeneration either as a result of physical injury, age, disease, genetic propensity or a combination thereof. The degenerative disc may lessen the discs ability to allow relative movement between adjacent vertebrae and reduce its cushioning characteristics and as the disc breaks down the spacing between adjacent vertebras will be reduced. The rupturing, tearing of the disc may also lead to a condition known as spinal stenosis. Spinal stenosis is a progressive narrowing if the opening of the spinal canal. Each vertebra has a hole or channel passing through it. These holes are in alignment and form the spinal canal. A relatively large bundle of nerves known as the spinal cord runs through the spinal canal. When the spinal cord narrows the nerve roots in the spinal cord are compressed. The pressure on the nerve roots may cause chronic pain and numbness and in some instances cause loss of motive functions within the body. Most often the lower back and legs are affected by spinal stenosis. Cervical spinal stenosis is a narrowing if the vertebrae of the neck referred to as cervical vertebrae. In addition to exerting pressure on the spinal cord cervical stenosis can also put pressure on the arteries entering the spinal column thereby limiting the flow of blood to the other portions of the spinal cord.
Spinal stenosis and disc degeneration can be progressive diseases. Quite often these diseases are treated surgically by reestablishing a more normal spacing between the adjacent vertebrae. The restoration of the vertebral spacing may provide the necessary to relieve the pressure on the affected nerve tissue. The surgical procedure is intended to remove bone and other tissues that have entered the spinal canal or put pressure on the spinal cord. Often it is necessary to surgically remove the disc material as well. In general the restoration of the vertebral spacing is achieved by insertion of a spacer. The spacer element is formed from bone, metal or plastic material and enables the vertebrae to grow together, or fuse. Typically bone plates and or pedicle screws are utilized to stabilize and maintain proper alignment between adjacent vertebrae as they are fused together.
The installation of these intervertebral spacers significantly within the patient's body and proximate to the spine can be an invasive process requiring prolonged hospitalization and extended amounts of rehabilitation. It has been well recognized that a spacer device that can be deployed in a minimally invasive manner would result in a substantial improvement in the outcome of the procedure.